The present invention relates to the field of rechargeable power sources. More particularly, embodiments of the present invention provide a method for monitoring the condition of exhaustible power sources.
Today""s computer networks are usually comprised of multiple interconnected computer systems. Some of the computer systems are configured for use by individuals/users. These computer systems are normally referred to client or local computer systems. Other computer systems, also present within the network, are configured to facilitate the interaction between the client or local computer systems and the network to which they are connected. These other computer systems are commonly referred to as server or host computer systems. Additionally, it is common for many of today""s large companies to have hundreds or thousands of servers and client computer systems.
Further, both the server and client computer systems generate vast amounts of data containing a nearly endless variety of information. Portions of the data can contain information that can be considered mission critical and, as such, needs to be retained for future use and/or stored in a relatively permanent manner.
Currently there are numerous types of data storage systems that are designed to store the vast amounts of data. Examples of various data storage systems can include, but are not limited to, tape backup, disk mirroring, CD storage, multiple intercoupled data storage devices, and others.
A commonality among many types of data storage systems is the requirement of a power source, e.g., AC mains. Another similarity among many types of data storage systems is that data is first placed in a buffer or cache memory before it is written to a storage device or to an array of storage devices.
Brown-outs and black-outs, natural disasters, acts of terrorism, power generator failures, fires, and downed power lines, are but a few of the types of occurrences that can cause AC mains to become non-functional. Further, when an AC main fails, it is quite common for any information that was placed in the buffer or cache to be lost. This is especially disadvantageous for important information that had yet to be written to a data storage system.
To overcome this disadvantage, many data storage devices are coupled with a UPS (uninterruptible power supply) that provides power when there is an AC main failure. Another method of providing backup power includes placing batteries on the computer system board. Yet another method of providing backup power is to place a battery on the controller, and when the system is rebooted, there is an image of the data that was placed in the cache, which is then regenerated.
A disadvantage to batteries is that high current batteries, e.g., NiCad batteries, have been used mainly in the power tool arena and other low tech, non-mission critical environments. Further, high tech battery applications have been utilized in laptop batteries, which do not require the high current, high temperature demand of large storage systems, e.g., rack mounted RAID systems.
Conventionally, when there is a power failure, the data storage system quickly dumps the entire cache into a designated portion of one or two drives. By virtue of all of the drives not being used during the dump, battery backup loads are much smaller.
Disadvantageously, backup batteries can, over time, lose some of their ability to provide a consistent backup charge. It is common for backup batteries to have their ability to hold a charge diminished. In a worst case scenario, a battery may not have the ability to hold a charge for any period of time, thus causing a loss of data by not providing the backup power as presumed. Accordingly, if an AC main goes down, there is a possibility that the backup battery may not be able to store enough energy long enough to enable writing of the cache before battery power is exhausted.
Additionally disadvantageous is that in certain instances, checking or testing the condition of the battery can itself have a detrimental effect on the battery""s ability to hold a charge. For example, many battery manufacturers recommend a complete discharge of the battery periodically in order to test the device. In a high temperature, high current environment, e.g., multiple intercoupled data storage devices such as a RAID system, a complete discharge of the battery can cause elevated temperatures within the data storage system as well as in the battery. It is well known that elevated temperatures in a data storage system can severely and detrimentally effect the operation of the data storage system. Further disadvantageous is that by subjecting the battery to increased temperatures, the ability of the battery to be recharged is substantially reduced. Additionally disadvantageous is that continued complete discharge/recharge of a battery increases, in many instances, the occurrence of battery failure, the complete inability of a battery to hold any charge.
Thus a need exists for an improved method to monitor the condition of a backup battery. A further need exists for a method for testing the condition of the backup battery in a server system that does not adversely affect the condition of the backup battery or degrade the performance of the system.
Embodiments of the present invention are drawn to providing a method and system for monitoring the condition of a backup battery that does not adversely effect the condition of the backup battery.
In one embodiment, a method for battery condition testing comprises interrupting AC power service to a data storage system which causes an exhaustible power source to provide operating power to the data storage system. The exhaustible power source is coupled to the data storage system. The data storage system includes a data buffer and/or cache memory. The exhaustible power source is adapted to provide operating power to the data storage system when the AC power service to the data storage system is interrupted. Particularly, the power source monitors the data buffer during periods of AC main interruption. The method is further comprised of discharging the exhaustible power source by operating the data storage system with the exhaustible power source for a specified period of time. The exhaustible power source passes the condition testing when the exhaustible power source provides operating power to the data storage system for the specified period of time. Importantly, the battery is only discharged for the period of time that it is expected to provide power during an actual interruption of the AC main. This time period is based on the time required to copy the data from the buffer to the disk drives. The method is further comprised of recharging the exhaustible power source subsequent to the exhaustible power source passing the condition testing.
These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures.